The invention relates to a device for the contact-free measurement of rotary movements of components moving relative to one another, with
a stator unit consisting of two asymmetrically built partial stator elements that leave empty two spacing openings between them, where at least one Hall unit is located in at least one spacing opening, and
where the partial stator elements are split in the shape of a partial ring into a large partial stator element and a small partial stator element, whereby the large partial stator element covers a range of greater than 180° and the small partial stator element of less than 180° of a circular arc, and
a rotor unit consisting of a magnet element that is supported by a magnet support element and that can be moved relative to the stator elements while maintaining an air gap,
whereby the magnet element consists of two magnetically bipolar magnet segment elements that are at least partially arranged in a first part made of a magnetically non-conducting material.
In addition, the invention relates to a device for monitoring an alterable operating parameter.
A device of the type mentioned above is known from DE 196 30 764 A1, where this device consists of a partial stator element that stretches across 240° and an additional partial stator element that stretches across 120°. Two radially oriented openings are located between the two partial stator elements. A Hall unit is located in one of the openings. A movable magnet element is located in the partial stator elements. Maintaining an air gap, a rotor unit with a bipolar magnet element is arranged in the two partial stator elements. The magnet element consists of two partial magnet elements with differing lengths. One partial magnet element can exhibit an angle range of greater than 180°. The magnet element is embedded in a synthetic compound.
The disadvantage of this device is that the manufacturing process for the radially oriented openings is very elaborate. In addition, the polarity of the magnet elements does not permit a full utilization of the angle magnification. The linearity of the output signal is negatively influenced due to the uneven lengths of the partial magnet elements of the magnet element.
Known from WO 95 14 911 A1, is the manufacture of the partial stator elements of stacks of sheet metal consisting of textured sheet metal. However, the individual sheets are provided with openings and are held together using an appropriate device. The profile of the magnetic flux is altered by the openings.
DE 100 54 123 A1 shows a rotation angle sensor where the stator elements are also built up from sheet metal stacks. Hall ICs are located in spacing openings between the partial stator elements and are offset from one another by 180°. Via input and output terminals, the Hall ICs are connected to a connector unit. However, the rotation angle sensor is only capable of measuring angles between 0° and 90°.
Monitoring an alterable operating parameter is known from both EP 0 457 033 B1 and WO 91 12 423 A1. They employ measuring devices that are designed with a combined power supply.
Disadvantageous is the fact that resistor combinations have been employed as the measuring devices. Because the resistor values need to be tapped and the resistance tracks as well as the taps encounter wear or even damage in the process, they are not entirely dependable for their monitoring function.
Known from DE 196 34 281 A1 is a rotation angle sensor with a stator unit that consists of three stator elements. A measuring element is located in an opening between two stator elements with a magnet element moving around said stator elements. The opening can be arranged tangentially. To achieve a measuring range of 110°, the third stator element must, however, be connected in a magnetically conducting manner with one of the other two stator elements.
Known from U.S. Pat. No. 4,107,601 is the arrangement of bars of a magnetic material at a rotor shaft using a flexible strip. However, this strip is used only to press the bars in a spaced manner to the shaft.
As a rule, rotation angle sensors allow for the measurement of angles between 0° and 90°.
Such a rotation angle sensor is known from WO 95 14 901 A1. It consists of a stationary and of a rotating formation. The stationary formation includes two crescent-shaped stator elements with a spacing opening between them and a Hall element located in said opening. The rotating formation exhibits a magnet element designed in a ring shape that is supported by a support unit and that can be moved around the stator element while maintaining an air gap.
Rotation angle sensors are also known to the applicant from WO 98 25 102 A1, DE 197 16 985 A1, DE 199 03 940 A1 and EP 1 024 267 A2.